Hi again,

Once you have the result in the form

In[]:= gridpos = GeoGridPosition[GeoPosition[{40, -90}], proj]
Out[]= GeoGridPosition[{702.282, 476.602}, {"Stereographic", ...}]

you can recover the latlon form using

In[]:= GeoPosition[gridpos]    
Out[]= GeoPosition[{40., -90.}]

The property "Data" can also be used to extract the coordinate numbers from a GeoPosition object.

Hi Jose,

Thanks for your explanations, gives me a lot of pointers to investigate further (I'm new to GIS).

How would I transform the other way around though, from a grid of Polar Stereographic coordinates to Lat/Lon?